While Houstonians were evacuating before the arrival of Hurricane Harvey, San Antonio mom Lilliana Castro was doing quite the opposite. She hopped in the car with her four children and headed straight into the storm’s path.

She wouldn’t have faced one of Houston’s most damaging storms on record unless it was urgent.

Her 11-year-old son, Tony, was due for surgery to remove the golf ball-sized tumor next to his brain stem. It would be his third surgery in four years.

“They thought I wasn’t going to come over here because of the storm, but for my son, I would brave any storm,” Castro told TODAY.

Courtesy of Hermann Memorial Hospital and Lilliana Castro

Kassandra, Isaac, Kayla, Lilliana and Tony Castro

Tony was just 7 when he was diagnosed with brain cancer. After two surgeries and chemotherapy, a CT scan about a month ago revealed the cancer was back.

Castro sought treatment for Tony in Houston because she had no other options. After Tony’s first surgery in 2014, doctors in San Antonio felt it was unsafe to continue treatment. A registered nurse at IASIS Healthcare and a devoted mother, Castro refused to give up.

Tony had received radiation in Houston, so she sought help there. Dr. David Sandberg, a pediatric neurosurgeon at Children’s Memorial Hermann Hospital, gave her hope. He performed Tony’s second surgery in Oct. 2016.

Ever since, Lilliana has been making the 200-mile drive east to Houston about every six weeks.

Lilliana Castro and Memorial Hermann-Texas Medical Center

Lilliana Castro captured a photo of Houston floodwaters on her ride to Children's Memorial Hermann Hospital during Hurricane Harvey.

By the time she hit the road on Aug. 26, Harvey had already made landfall. The Category 4 hurricane turned what should have been a three-hour trip into five hours of nightmarish driving.

“Out there when you are on the highways, where you can see all the water all around, it is a very scary sight,” she said.

The trip didn't get any easier when the family arrived at their hotel in the city’s Galleria area.

The streets were so flooded the family could barely find food. Making it to Children’s Memorial for Tony’s Aug. 28 surgery seemed impossible.

“I went out trying to see where I could get closer to the hospital area, but it was just flooded everywhere,” Castro said.

'Helping After Harvey': Truckloads of donations reach Houston

'Helping After Harvey': Truckloads of donations reach Houston

Meanwhile, Sandberg made a call to try to help his young patient. A friend put him in touch with a local chef who had a big truck.

Jeff Weinstock, owner of wholesale bakery and butcher shop Cake & Bacon, had been out assisting with rescue missions and food deliveries. He agreed to pick up the Castros in his Ford F150.

Leaving their hotel for the first time, the scene that met Lilliana and her family was shocking. Major roads were flooded, while cars, trees and even homes were submerged.

Tony, for one, was impressed: Weinstock took an exit ramp the wrong way to get onto the Interstate 45 toward the hospital. No one was there to care.

What should have been a 15 minute trip, took about 45. But with Weinstock as their guide, the family arrived safely and on time for Tony’s surgery.

“It just kind of hit me after dropping him off, it was cool to be a part of that experience and to be so helpful,” Weinstock told TODAY.

Lilliana Castro and Memorial Hermann-Texas Medical Center

Tony Castro with a therapy dog following his surgery.

At the hospital, operations were not quite business as usual. Thanks to building code updates input after tropical storm Allison in 2001, the hospital managed to avoid power outages or significant flooding.

But all elective surgeries and outpatient procedures were postponed to make room for incoming patients. Many hospital staffers slept at the hospital.

Tony’s surgery was important enough that Sandberg felt it couldn’t wait.

“If the tumor grew even a little bit more, he was going to get very sick from increased pressure in the brain, and was going to show up in the emergency room vomiting, lethargic, even comatose,” Sandberg told TODAY.

Lilliana Castro and Memorial Hermann-Texas Medical Center

Dr. David Sandberg and Tony Castro. The doctor removed 90 percent of the boy's brain tumor.

In the U.S., there are about 4,000 new brain tumor diagnoses in children each year, according to Sandberg.

The Centers for Disease Control reports brain cancer has replaced Leukemia as the leading cause of cancer death in individuals 19 or younger.

In Tony’s case, the tumor’s position against his brainstem was cause for concern.

Sandberg and his team performed Tony’s five-hour procedure, successfully removing 90 percent of the tumor.

The boy emerged from surgery Monday, exhausted but itching to get back home.